1. Field of the Invention
The present invention relates to a surface coil of the type used for inducing and acquiring nuclear magnetic resonance signals in an examination subject.
2. Description of the Prior Art
During Examination in a nuclear magnetic resonance apparatus, an examination subject is situated in a uniform fundamental magnetic field. A surface coil is positioned in the proximity of the region of the patient to be examined and, by the generation of a radio-frequency pulse in the presence of an alternating magnetic field, nuclear spins of the examination subject are excited. The nuclear magnetic resonance signal emitted in response to such spins is picked up by the surface coil, and is stored in the NMR apparatus.
The use of surface coils in phosphorous spectroscopy are described, for example, in articles appearing in "Journal Of Magnetic Resonance," 60, pages 268-279 (1984) and "Journal Of Magnetic Resonance," 55, pages 164-169 (1983).
With surface coils for inducing nuclear spin and receiving the resulting resonance signal, a higher image quality (better signal-to-noise ratio) is achieved, and thus a higher detail discrimination is possible because smaller regions can be examined. Surface coils are known which can be geommetrically adapted to the examination region of interest.
Surface coils are generally used in combination with a tunable resonant circuit. A disadvantage of this arrangement is the accompanying sensitivity to exterior electrical noise and to movement of the examination subject, which leads to phase errors. Other disadvantages of such known systems are the complex manufacture of the electrical matching unit, the relative inflexibility in the use of such a complex system, the unwildiness for application to measurements of the human body, and long measurement preparation time resulting from the tuning operation.